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(11) | EP 2 583 843 B1 |
(12) | EUROPEAN PATENT SPECIFICATION |
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(54) |
Method, apparatus, and program for detecting tire having decreased air pressure Verfahren, Vorrichtung und Programm zum Erkennen eines Reifens mit verringertem Luftdruck Procédé, appareil et programme de détection de pneu ayant une pression d'air réduite |
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Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). |
{Technical Field}
{Background Art}
{Citation List}
{Patent Literature}
{Patent Literature 1} Japanese Unexamined Patent Publication No. 2005-126013
{Patent Literature 2} Japanese Unexamined Patent Publication No. 2005-127975
{Patent Literature 3} Japanese Unexamined Patent Publication No. 2005-153544
{Summary of Invention}
{Technical Problem}
{Solution to Problem}
(1) In accordance with the present invention, there is provided a method for detecting a tire having a decreased air pressure (hereinafter also simply referred to as "detection method") based on wheel rotation information to be obtained from the tire attached to a vehicle in which there is a predetermined difference between a front wheel load and a rear wheel load, including: a step of acquiring the wheel rotation information to be obtained from the tire; a step of storing the wheel rotation information; a step of acquiring a load sensitivity of a tire dynamic loaded radius due to a load shift during a turning; a step of acquiring a speed dependency of the load sensitivity; a step of comparing a load sensitivity of a tire dynamic loaded radius at a speed acquired based on the speed dependency with preliminarily stored load sensitivities of dynamic loaded radiuses of various tires; a step of estimating a decreased pressure sensitivity of the tire dynamic loaded radius based on a result of the comparison; and a step of determining that the tire has a decreased air pressure based on a result of the estimation, wherein the speed dependency is acquired from a change of a front and rear wheel speed ratio.
(2) In the detection method of (1), the speed dependency may be acquired by "(front and rear wheel speed ratio - 1)/front and rear wheel load difference".
(3) The detection method of (1) or (2) may include a step of correcting the speed dependency acquired from the change of the front and rear wheel speed ratio based on a relation between a speed dependency of a load sensitivity acquired from a lateral acceleration and a left and right wheel speed difference and the speed dependency acquired from the change of the front and rear wheel speed ratio, the relation being preliminarily acquired for each vehicle type.
(4) The detection method of (1) to (3) may include a step of rejecting data of the front and rear wheel speed ratio when an absolute value of wheel torque of the vehicle exceeds 60 Nm.
(5) In accordance with the present invention, there is also provided an apparatus for detecting a tire having a decreased air pressure (hereinafter also simply referred to as "detection apparatus") based on wheel rotation information to be obtained from the tire attached to a vehicle in which there is a predetermined difference between a front wheel load and a rear wheel load, including: wheel rotation information obtaining means for acquiring the wheel rotation information to be obtained from the tire; storage means for storing the wheel rotation information; load sensitivity obtaining means for acquiring a load sensitivity of a tire dynamic loaded radius due to a load shift during a turning; speed dependency obtaining means for acquiring a speed dependency of the load sensitivity; comparison means for comparing a load sensitivity of a tire dynamic loaded radius at a speed acquired based on the speed dependency with preliminarily stored load sensitivities of dynamic loaded radiuses of various tires; decreased pressure sensitivity estimation means for estimating a decreased pressure sensitivity of the tire dynamic loaded radius based on a result of the comparison; and determination means for determining that the tire has a decreased air pressure based on a result of the estimation, wherein the speed dependency is acquired from a change of a front and rear wheel speed ratio.
(6) In the detection apparatus of (5), the speed dependency may be acquired by "(front and rear wheel speed ratio - 1)/front and rear wheel load difference".
(7) The detection apparatus of (5) or (6) may include correction means for correcting the speed dependency acquired from the change of the front and rear wheel speed ratio based on a relation between a speed dependency of a load sensitivity acquired from a lateral acceleration and a left and right wheel speed difference and the speed dependency acquired from the change of the front and rear wheel speed ratio, the relation being preliminarily acquired for each vehicle type.
(8) The detection apparatus of (5) to (7) may include rejection means for rejecting data of the front and rear wheel speed ratio when an absolute value of wheel torque of the vehicle exceeds 60 Nm.
(9) In accordance with the present invention, there is further provided a program for detecting a tire having a decreased air pressure based on wheel rotation information to be obtained from the tire attached to a vehicle in which there is a predetermined difference between a front wheel load and a rear wheel load, the program making a computer function as: wheel rotation information obtaining means for acquiring the wheel rotation information to be obtained from the tire; storage means for storing the wheel rotation information; load sensitivity obtaining means for acquiring a load sensitivity of a tire dynamic loaded radius due to a load shift during a turning; speed dependency obtaining means for acquiring a speed dependency of the load sensitivity; comparison means for comparing a load sensitivity of a tire dynamic loaded radius at a speed acquired based on the speed dependency with preliminarily stored load sensitivities of dynamic loaded radiuses of various tires; decreased pressure sensitivity estimation means for estimating a decreased pressure sensitivity of the tire dynamic loaded radius based on a result of the comparison; and determination means for determining that the tire has a decreased air pressure based on a result of the estimation, wherein the speed dependency is acquired from a change of a front and rear wheel speed ratio.
{Advantageous Effects of Invention}
{Brief Description of Drawings}
Fig. 1 is a block diagram illustrating one embodiment of a detection apparatus of the present invention;
Fig. 2 is a block diagram illustrating an electrical configuration of the detection apparatus shown in Fig. 1;
Fig. 3 is an illustrative view of how to acquire a load sensitivity;
Fig. 4 illustrates one example of a relation between a decreased pressure sensitivity and the load sensitivity; and
Fig. 5 illustrates one example of a running pattern during a test.
{Description of Embodiments}
[Speed Dependency of Load Sensitivity]
[How to Acquire Relation between Both Speed Dependencies]
[Load Sensitivity and Decreased Pressure Sensitivity]
[Test Example]
Tire A(215/60R16 94H) | ||||
40 kph | 60 kph | 80 kph | 100 kph | |
DEL2@LLVW | 0.0030 | 0.0031 | 0.0035 | 0.0034 |
DEL2@GVW | 0.0011 | 0.0010 | 0.0011 | 0.0009 |
Tire B(225/50R17 93V) | ||||
40 kph | 60 kph | 80 kph | 100 kph | |
DEL2@LLVW | 0.0032 | 0.0031 | 0.0028 | 0.0026 |
DEL2@GVW | 0.0011 | 0.0010 | 0.0011 | 0.0010 |
[Detection of Tire Having Decreased Air Pressure]
(1) During the actual running, as described for example in Patent Literatures 1 to 3, the load sensitivity of the tire dynamic loaded radius due to the load shift during the turning is acquired. Specifically, from the inclination of the regression line of the lateral G obtained from wheel speed information or a lateral acceleration sensor and the left and right wheel speed difference similarly obtained from the wheel speed information, the load sensitivity of the tire dynamic loaded radius due to the load shift during the turning is acquired.
(2) Then, by measuring "(front and rear wheel speed ratio - 1)/ front and rear wheel load difference", the speed dependency of the load sensitivity of the dynamic loaded radius is acquired. Regarding the front and rear wheel load difference, an approximate value is preliminarily known for each vehicle type if in a light load state.
(3) In the above step (1), when the vehicle speed at the time of being capable of acquiring the load sensitivity (sampling the data of the lateral G and the left and right wheel speed difference to an extent that the regression line can be drawn) is V, the load sensitivity of the tire dynamic loaded radius at another vehicle speed V' can be acquired with using the above-described formula (1).
(4) The load sensitivity of the tire dynamic loaded radius reflecting the speed dependency acquired in the above step (3) is compared with the preliminarily measured load sensitivities of the dynamic loaded radiuses of the various tires. As a result of the comparison, the tire attached to the vehicle is specified, and the decreased pressure sensitivity of the specified tire (decreased pressure sensitivities are stored in the ROM 2c together with the load sensitivities) is estimated. As shown in Fig. 4, as a result of measurement of the various tires, in a case where the relation between the load sensitivity and the decreased pressure sensitivity is already known, the decreased pressure sensitivity can be estimated from the regression line thereof.
(5) By changing a threshold value for decreased pressure determination based on the estimation result of the decreased pressure sensitivity, it is determined more precisely whether or not the tire has a decreased air pressure.
(6) When it is determined that the tire has a decreased air pressure, the alarm unit 5 is activated to invite an attention of the driver.
{Reference Signs List}
a step of acquiring the wheel rotation information to be obtained from the tire;
a step of storing the wheel rotation information;
a step of acquiring a load sensitivity of a tire dynamic loaded radius due to a load shift during a turning;
a step of acquiring a speed dependency of the load sensitivity;
a step of comparing a load sensitivity of a tire dynamic loaded radius at a speed acquired based on the speed dependency with preliminarily stored load sensitivities of dynamic loaded radiuses of various tires;
a step of estimating a decreased pressure sensitivity of the tire dynamic loaded radius based on a result of the comparison; and
a step of determining that the tire has a decreased air pressure based on a result of the estimation, characterized in that
the speed dependency is acquired from a change of a front and rear wheel speed ratio.
wheel rotation information obtaining means (1) for acquiring the wheel rotation information to be obtained from the tire;
storage means (2d) for storing the wheel rotation information;
load sensitivity obtaining means (2b) for acquiring a load sensitivity of a tire dynamic loaded radius due to a load shift during a turning;
speed dependency obtaining means (2b) for acquiring a speed dependency of the load sensitivity;
comparison means (2b) for comparing a load sensitivity of a tire dynamic loaded radius at a speed acquired based on the speed dependency with preliminarily stored load sensitivities of dynamic loaded radiuses of various tires;
decreased pressure sensitivity estimation means (2b) for estimating a decreased pressure sensitivity of the tire dynamic loaded radius based on a result of the comparison; and
determination means for determining that the tire has a decreased
air pressure based on a result of the estimation, characterized in that the speed dependency is acquired from a change of a front and rear
wheel speed ratio.
wheel rotation information obtaining means for acquiring the wheel rotation information to be obtained from the tire;
storage means for storing the wheel rotation information;
load sensitivity obtaining means for acquiring a load sensitivity of a tire dynamic loaded radius due to a load shift during a turning;
speed dependency obtaining means for acquiring a speed dependency of the load sensitivity;
comparison means for comparing a load sensitivity of a tire dynamic loaded radius at a speed acquired based on the speed dependency with preliminarily stored load sensitivities of dynamic loaded radiuses of various tires;
decreased pressure sensitivity estimation means for estimating a decreased pressure sensitivity of the tire dynamic loaded radius based on a result of the comparison; and
determination means for determining that the tire has a decreased
air pressure based on a result of the estimation, characterized in that the speed dependency is acquired from a change of a front and rear wheel speed ratio.
einen Schritt eines Erlangens der Radrotationsinformation, die von dem Reifen zu beschaffen ist;
einen Schritt eines Speicherns der Radrotationsinformation;
einen Schritt eines Erlangens einer Lastempfindlichkeit eines dynamischen belasteten Radius des Reifens aufgrund einer Lastverschiebung während einer Kurvenfahrt;
einen Schritt eines Erlangens einer Drehzahlabhängigkeit der Lastempfindlichkeit;
einen Schritt eines Vergleichens einer Lastempfindlichkeit eines dynamisch belasteten Radius des Reifens bei einer Drehzahl, erlangt auf der Basis der Drehzahlabhängigkeit, mit vorläufig gespeicherten Lastempfindlichkeiten von dynamisch belasteten Radien von verschiedenen Reifen;
einen Schritt eines Schätzens einer verringerten Druckempfindlichkeit des dynamisch belasteten Radius des Reifens auf der Basis eines Ergebnisses des Vergleichs; und
einen Schritt eines Ermittelns, dass der Reifen einen verringerten Luftdruck aufweist, auf der Basis eines Ergebnisses der Schätzung,
dadurch gekennzeichnet, dass
die Drehzahlabhängigkeit aus einer Änderung eines Vorder- und Hinterrad-Drehzahlverhältnisses erlangt wird.
ein Radrotationsinformations-Beschaffungsmittel (1) zum Erlangen der Radrotationsinformation, die von dem Reifen zu beschaffen ist;
ein Speichermittel (2d) zum Speichern der Radrotationsinformation;
ein Lastempfindlichkeits-Beschaffungsmittel (2b) zum Erlangen einer Lastempfindlichkeit eines dynamisch belasteten Radius des Reifens aufgrund einer Lastverschiebung während einer Kurvenfahrt;
ein Drehzahlabhängigkeits-Beschaffungsmittel (2b) zum Erlangen einer Drehzahlabhängigkeit der Lastempfindlichkeit;
ein Vergleichsmittel (2b) zum Vergleichen einer Lastempfindlichkeit eines dynamisch belasteten Radius des Reifens bei einer Drehzahl, die auf der Basis der Drehzahlabhängigkeit beschafft wird, mit vorläufig gespeicherten Lastempfindlichkeiten von dynamisch belasteten Radien von verschiedenen Reifen;
ein Schätzmittel einer verringerten Druckempfindlichkeit (2b) zum Schätzen einer verringerten Druckempfindlichkeit des dynamisch belasteten Radius des Reifens auf der Basis eines Ergebnisses des Vergleichs; und
ein Ermittlungsmittel zum Ermitteln, dass der Reifen einen verringerten Luftdruck aufweist, auf der Basis eines Ergebnisses der Schätzung,
dadurch gekennzeichnet, dass
die Drehzahlabhängigkeit aus einer Änderung eines Vorder- und Hinterrad-Drehzahlverhältnisses erlangt wird.
ein Radrotationsinformations-Beschaffungsmittel zum Erlangen der Radrotationsinformation, die von dem Reifen zu beschaffen ist;
ein Speichermittel zum Speichern der Radrotationsinformation;
ein Lastempfindlichkeits-Beschaffungsmittel zum Erlangen einer Lastempfindlichkeit eines dynamisch belasteten Radius des Reifens aufgrund einer Lastverschiebung während einer Kurvenfahrt;
ein Drehzahlabhängigkeits-Beschaffungsmittel zum Erlangen einer Drehzahlabhängigkeit der Lastempfindlichkeit;
ein Vergleichsmittel zum Vergleichen einer Lastempfindlichkeit eines dynamisch belasteten Radius des Reifens bei einer Drehzahl, die auf der Basis der Drehzahlabhängigkeit erlangt wird, mit vorläufig gespeicherten Lastempfindlichkeiten von dynamisch belasteten Radien von verschiedenen Reifen;
ein Schätzmittel einer verringerten Druckempfindlichkeit zum Schätzen einer verringerten Druckempfindlichkeit des dynamisch belasteten Radius des Reifens auf der Basis eines Ergebnisses des Vergleichs; und
ein Ermittlungsmittel zum Ermitteln, dass der Reifen einen verringerten Luftdruck aufweist, auf der Basis eines Ergebnisses der Schätzung,
dadurch gekennzeichnet, dass
die Drehzahlabhängigkeit aus einer Änderung eines Vorder- und Hinterrad-Drehzahlverhältnisses erlangt wird.
une étape d'acquisition des informations de rotation de roue devant être obtenues à partir du pneu ;
une étape de stockage des informations de rotation de roue ;
une étape d'acquisition d'une sensibilité de charge d'un rayon dynamique de roulement sous charge de pneu en raison d'un déplacement de charge pendant un virage ;
une étape d'acquisition d'une dépendance de vitesse de la sensibilité de charge ;
une étape de comparaison d'une sensibilité de charge d'un rayon dynamique de roulement sous charge de pneu à une vitesse acquise sur la base de la dépendance de vitesse avec des sensibilités de charge stockées préalablement de rayons dynamiques de roulement sous charge de divers pneus ;
une étape d'estimation d'une sensibilité de pression diminuée du rayon dynamique de roulement sous charge de pneu sur la base d'un résultat de la comparaison ; et
une étape de détermination selon laquelle le pneu a une pression d'air diminuée sur la base d'un résultat de l'estimation, caractérisé en ce que
la dépendance de vitesse est acquise à partir d'un changement d'un rapport de vitesse de roues avant et arrière.
des moyens d'obtention d'informations de rotation de roue (1) pour acquérir les informations de rotation de roue devant être obtenues à partir du pneu ;
des moyens de stockage (2d) pour stocker les informations de rotation de roue ;
des moyens d'obtention de sensibilité de charge (2b) pour acquérir une sensibilité de charge d'un rayon dynamique de roulement sous charge de pneu en raison d'un déplacement de charge pendant un virage ;
des moyens d'obtention de dépendance de vitesse (2b) pour acquérir une dépendance de vitesse de la sensibilité de charge ;
des moyens de comparaison (2b) pour comparer une sensibilité de charge d'un rayon dynamique de roulement sous charge de pneu à une vitesse acquise sur la base de la dépendance de vitesse avec des sensibilités de charge stockées préalablement de rayons dynamiques de roulement sous charge de divers pneus ;
des moyens d'estimation de sensibilité de pression diminuée (2b) pour estimer une sensibilité de pression diminuée du rayon dynamique de roulement sous charge de pneu sur la base d'un résultat de la comparaison ; et
des moyens de détermination pour déterminer que le pneu a une pression d'air diminuée sur la base d'un résultat de l'estimation, caractérisé en ce que
la dépendance de vitesse est acquise à partir d'un changement d'un rapport de vitesse de roues avant et arrière.
des moyens d'obtention d'informations de rotation de roue pour acquérir les informations de rotation de roue devant être obtenues à partir du pneu ;
des moyens de stockage pour stocker les informations de rotation de roue ;
des moyens d'obtention de sensibilité de charge pour acquérir une sensibilité de charge d'un rayon dynamique de roulement sous charge de pneu en raison d'un déplacement de charge pendant un virage ;
des moyens d'obtention de dépendance de vitesse pour acquérir une dépendance de vitesse de la sensibilité de charge ;
des moyens de comparaison pour comparer une sensibilité de charge d'un rayon dynamique de roulement sous charge de pneu à une vitesse acquise sur la base de la dépendance de vitesse avec des sensibilités de charge stockées préalablement de rayons dynamiques de roulement sous charge de divers pneus ;
des moyens d'estimation de sensibilité de pression diminuée pour estimer une sensibilité de pression diminuée du rayon dynamique de roulement sous charge de pneu sur la base d'un résultat de la comparaison ; et
des moyens de détermination pour déterminer que le pneu a une pression d'air diminuée sur la base d'un résultat de l'estimation, caractérisé en ce que
la dépendance de vitesse est acquise à partir d'un changement d'un rapport de vitesse de roues avant et arrière.
REFERENCES CITED IN THE DESCRIPTION
Patent documents cited in the description